Technical Abstract:
We conduct research on use of a combination of appropriate companion crops (i.e., “push-pull” intercropping) with natural enemy refuges to enhance the effectiveness of biological control agents in suppressing populations of the invasive whitefly, Bemisia tabaci. We continue to identify plants or products that repel whiteflies (“push” strategy) or attract natural enemies into crops (“pull” strategy) to manage whitefly populations in the field. We studied the effect of giant red mustard plants (Brassica juncea) and commercial products to control the whiteflies. In laboratory no-choice tests, whiteflies were released in potted squash plants sprayed with mustard oil, garlic oil, horticultural petroleum oil, hot pepper wax and a water control. We found that the plants sprayed with the oils had significantly lower numbers of whiteflies compared to those sprayed with hot pepper wax and water alone. It is possible that whiteflies were repelled by volatiles from the oils. In a separate study, we studied the effect of plant volatiles on whitefly behavior using specialized odor detecting equipment. We found that whiteflies were repelled by giant red mustard plants. Our results indicate that giant red mustard plants and commercial oils such as mustard, garlic and horticultural oils are promising control agents against whiteflies in vegetable plants.